1. Field of the Invention
The invention relates to a driving control for a vehicle and a driving control method for a vehicle. Particularly, the invention relates to downshift control at a coasting time.
2. Description of the Related Art
A driving control apparatus for a vehicle is known, which includes (a) an engine which generates power by fuel combustion, (b) a transmission which achieves plural speeds, gear ratios of which are different from each other, by changing engagement/disengagement states of plural frictional engagement devices, and (c) coasting time downshift control means for disengaging a high speed side frictional engagement device and applying torque to a low speed side frictional engagement device such that an engine speed is increased when downshifting of the transmission is automatically performed at a coasting time (for example, refer to Japanese Patent Laid-Open Publication No. 11-287317 (claim 6, and FIG. 7)). Also, a technology is widely employed, in which fuel supply to the engine is stopped (fuel cut is performed) for improving fuel economy when a predetermined fuel cut condition including a condition that the vehicle is coasting is satisfied (refer to Japanese Patent Laid-Open Publication No. 9-53718).
However, in the case where a signal for downshifting of the transmission is output while fuel cut is performed at the coasting time, and then the engine speed is being increased according to the control of torque of the low speed side frictional engagement device by the coasting time downshift control means, when fuel cut is cancelled, for example, due to the operation of auxiliaries such as an air conditioner and fuel supply is restarted, torque of an output shaft (driving torque of a vehicle) may be suddenly changed due to a decrease in a load of the engine (an engine brake force), which may cause a driver to feel uncomfortable. Particularly, since downshifting at the coasting time (hereinafter, refer to as coasting time downshifting) is automatically performed when the driver does not intend to change torque, the driver may feel a shock (a change in the torque) sensitively even if the shock is relatively small, which is inconvenient.